DE 199 04 679 A1 teaches a laser-adjusted measuring aid for workers in woods and forests. The measuring aid disclosed in it is intended to replace a cross-cut measuring rod, a measuring tape, or a slide caliper. To this end two laser pointers are arranged at an angle to one another in a holder. The laser beams form a type of distance compasses with which a defined length can be measured at a predetermined interval of the holder to the piece of wood to be measured. The holder is fastened to this end, e.g., on a belt, and adjusted or set to the particular height of the belt from the ground below. Two lasers are required in this measuring aid. An adjustment must be made on the holder for a defined distance measuring as well as for the height of the arrangement of the holder and the angle between the two lasers. This is especially difficult when working on a slope.
DE 197 08 467 A1 teaches a device for indirect and multi-dimensional measuring and a position aid for indicating theoretical positions. The compass-like distance measuring device comprises a mechanical and an optical shank. The angle between the mechanical object shank and the sensor axis, which represents the optical shank, is adjustable. This hand measuring device has the disadvantage that although a certain distance can be displayed as when using a cross-cut measuring rod, the starting and end points of the distance must be marked, e.g., with a pencil, on the workpiece to be measured. The tool must be taken up by the worker in a subsequent work step and the workpiece must be worked.
In addition to other disadvantages, the described auxiliary means are not especially easy to use. If, for example, tree trunks are being crosscut, the pre-set measurement, e.g., 1 meter, must first be characterized with the auxiliary device and, if necessary, with a pencil or some other marking device. Then, the tool must be taken in the hand and the tree trunk crosscut to the required measurement. The measuring tool is restarted, then the marking performed and the tree trunk crosscut again, etc. This requires a significant amount of time and is problematic for the workers.
US 2002/0069542 A1 teaches a motor saw that comprises a laser for marking a certain length of the tree trunk to be cut off. The laser is arranged on one side of the motor saw. The crosscutting of the trunk can therefore only take place from one side. Moreover, it is arranged on a very exposed position of the saw and is therefore not suitable for resisting the rough conditions in forestry work.
Therefore, an object of the present invention is creating a display device that permits a rapid and comfortable working of a workpiece at regular intervals under difficult environmental conditions.